Semiconductor memory device and method of operating same

ABSTRACT

There are many inventions described and illustrated herein. In a first aspect, the present invention is directed to a memory device and technique of reading data from and writing data into memory cells of the memory device. In this regard, in one embodiment of this aspect of the invention, the memory device and technique for operating that device that minimizes, reduces and/or eliminates the debilitating affects of the charge pumping phenomenon. This embodiment of the present invention employs control signals that minimize, reduce and/or eliminate transitions of the amplitudes and/or polarities. In another embodiment, the present invention is a semiconductor memory device including a memory array comprising a plurality of semiconductor dynamic random access memory cells arranged in a matrix of rows and columns. Each semiconductor dynamic random access memory cell includes a transistor having a source region, a drain region, a electrically floating body region disposed between and adjacent to the source region and the drain region, and a gate spaced apart from, and capacitively coupled to, the body region. Each transistor includes a first state representative of a first charge in the body region, and a second data state representative of a second charge in the body region. Further, each row of semiconductor dynamic random access memory cells includes an associated source line which is connected to only the semiconductor dynamic random access memory cells of the associated row.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/840,009,filed May 6, 2004 now abandoned, which claims priority to: (1) U.S.Provisional Application Ser. No. 60/470,384, entitled “Method ofOperating Semiconductor Memory Device”, filed May 13, 2003; and (2) U.S.Provisional Application Ser. No. 60/470,318, entitled “Dual Port OneTransistor DRAM Memory Cell and Extension to Multi-Port Memory Cell”,filed May 13, 2003 (hereinafter collectively “the ProvisionalApplications”). The contents of the Provisional Applications areincorporated by reference herein in their entirety.

BACKGROUND

This invention relates to a semiconductor dynamic random access memory(“DRAM”) cell, array and/or device and method of controlling and/oroperating a semiconductor memory cell array and/or device; and moreparticularly, in one aspect, to a semiconductor dynamic random accessmemory (“DRAM”) cell, array and/or device wherein the memory cellincludes an electrically floating body in which an electrical charge isstored.

There are many different types and/or forms of DRAM cells, including,for example, a semiconductor memory cell consisting of an accesstransistor and a capacitor, which stores an electric charge representinga bi-stable memory state. The access transistor serves as a switch forcontrolling the charging and discharging of the capacitor as well asreading and writing of the logic states into the capacitor (i.e.,charging or discharging the capacitor).

Although significant integration densities can be achieved with DRAMdevices employing one transistor—one capacitor memory cells, suchdevices tend to be limited or restricted with respect to the size of thememory cell. In this regard, conventional techniques employ stackedand/or trench capacitor approaches, whereby the capacitor is partiallydisposed above and/or below an access transistor.

In addition, DRAM devices employing one transistor—one capacitor memorycells tend to be fabricated using manufacturing processes that aredifferent from and/or incompatible with manufacturing processes forlogic devices (for example, microprocessors). As a result, integrationof one transistor—one capacitor memory cells into logic devices is oftencomplicated and expensive.

Another type of dynamic random access memory cell is described andillustrated in non-provisional patent application entitled“Semiconductor Device”, which was filed on Jun. 10, 2003, and assignedSer. No. 10/450,238 (hereinafter “Semiconductor Memory Device PatentApplication”). With reference to FIGS. 1A and 1B, the SemiconductorMemory Device Patent Application discloses, among other things,semiconductor DRAM device 10 in which each memory cell 12 consists oftransistor 14 having gate 16, body region 18, which is electricallyfloating, source region 20 and drain region 22. The body region 18 isdisposed between and adjacent to source region 20 and drain region 22.Data is written into or read from a selected memory cell by applyingsuitable control signals to a selected word line(s) 24, a selectedsource line(s) 26 and/or a selected bit line(s) 28. In response, chargecarriers are accumulated in or emitted and/or ejected from electricallyfloating body region 18 wherein the data states are defined by theamount of carriers within electrically floating body region 18.

In particular, in one embodiment, the memory cell of the SemiconductorMemory Device Patent Application operates by accumulating in oremitting/ejecting majority carriers (electrons or holes) 30 from bodyregion 18 of N-channel transistors. (See, FIGS. 2A and 2B). In thisregard, accumulating majority carriers (in this example, “holes”) 30 inbody region 18 of memory cells 12 via, for example, impact ionizationnear source region 20 and/or drain region 22, is representative of alogic high or “1” data state. (See, FIG. 2A). Emitting or ejectingmajority carriers 30 from body region 18 via, for example, forwardbiasing the source/body junction and/or the drain/body junction, isrepresentative of a logic low or “0”. (See, FIG. 2B).

Various techniques may be employed to read the data stored in (or writethe data into) a memory device of the Semiconductor Memory Device PatentApplication. For example, a current sense amplifier (not illustrated)may be employed to read the data stored in memory cells 12. In thisregard, a current sense amplifier may compare the memory cell current toa reference current, for example, the current of a reference cell (notillustrated). From that comparison, it may be determined whether memorycell 12 contained a logic high (relatively more majority carriers 30contained within body region 18) or logic low data state (relativelyless majority carriers 28 contained within body region 18).

Notably, transistor 14 may be a symmetrical or non-symmetrical device.Where transistor 14 is symmetrical, the source and drain regions areessentially interchangeable. However, where transistor 14 is anon-symmetrical device, the source or drain regions of transistor 14have different electrical, physical, doping concentration and/or dopingprofile characteristics. As such, the source or drain regions of anon-symmetrical device are typically not interchangeable.

The transistor 14 may be controlled using a negative drain voltage on,for example, bit line 28 i, to remove holes from electrically floatingbody region 18 through drain 22 to write a logic low (i.e., binary state“0”). Under this circumstances, a negative voltage applied to gate 16 ofthe other (non-selected) memory cells in the memory array of device 10may be necessary to avoid “leakage current” in other cells connected tothe same bit line 28 i when the negative bit line voltage is appliedduring the write (logic low) operation.

Other operations such as writing a logic high data state (binary “1”)and reading the data may be performed using positive voltages applied toword lines 24. As such, transistors 14 of device 10 are periodicallypulsed between a positive gate bias, which (1) drives majority carriers(holes for N-channel transistors) away from the interface between gateinsulator 32 and body region 18 of transistor 14 and (2) causes minoritycarriers (electrons for N-channel transistors) to flow from sourceregion 20 and drain region 22 into a channel formed below gate 16, and anegative gate bias, which causes majority carriers (holes for N-channeltransistors) to accumulate in or near the interface between gate 16 andbody region 18 of transistor 14.

With reference to FIG. 3A, a positive voltage applied to gate 16provides a positive gate bias which causes (1) a channel of minoritycarriers 34 to form beneath gate 16 and (2) accumulation of majoritycarriers 30 in body region 18 in an area “opposite” the interface ofgate 16 and body region 18. Here, minority carriers (i.e., electrons inan N-channel transistor) may flow in the channel beneath the interfaceof gate oxide 32 and floating body region 18 wherein some of theminority carriers 34 are “trapped” by or in defects within thesemiconductor (typically created or caused by the transition from onematerial type to another).

With reference to FIG. 3B, when a negative voltage is applied to gate16, the gate bias is negative which substantially eliminates the channelof minority carriers 34 beneath gate 16 (and gate oxide 34). However,some of minority carriers may remain “trapped” in the interface defects(illustrated generally by electrons 36).

Some of the trapped electrons 36 recombine with majority carriers whichare attracted to gate 16 (due to the negative gate bias), and, as such,the net charge of majority carriers 30 located in floating body region18 may decrease over time (see, for example, FIG. 3C). This phenomenonmay be characterized as charge pumping. Thus, pulsing between positiveand negative gate biases (during read and write operations) may reducethe net quantity of charge in memory cell 12, which, in turn, maygradually eliminate the data stored in memory cell 12.

Notably, for the efficient charge pumping phenomenon to occur, the freeelectron concentration at the surface (n_(e)) in inversion should besufficiently large that the interface traps can capture electrons duringthe time the transistor is in inversion. The time constant for electroncapture may be characterized as:

$\tau_{e} = \frac{1}{v_{th} \cdot \sigma_{n} \cdot n_{e}}$

Accordingly, in the case τ_(e)=3 ns (typical pulse duration in advancedDRAM memories), the thermal velocity V_(th)=1×10⁷ cm/s and the capturecross section σ_(n)=2×10⁻¹⁶ cm², at least n_(e)≈2×10¹⁷ cm⁻³ may berequired. Analogously, in accumula the free hole concentration at thesurface (n_(h)) should be sufficiently large that holes can recombinewith the captured electrons during the time transistor 14 is inaccumulation. If σ_(n)=σ_(p), n_(h)≈2×10¹⁷ cm⁻³ at least may be required(i.e., the efficient charge pumping effect exists if the gate voltage ininversion accumulates at least 2×10¹⁷ cm⁻³ electrons at the surface andthe gate voltage in accumulation accumulates at least 2×10¹⁷ cm⁻³holes).

Notably, the entire contents of the Semiconductor Memory Device PatentApplication, including, for example, the features, attributes,architectures, configurations, materials, techniques and advantagesdescribed and illustrated therein, are incorporated by reference herein.

SUMMARY OF THE INVENTION

There are many inventions described and illustrated herein. In a firstprincipal aspect, the present invention is a semiconductor memory arraycomprising a plurality of semiconductor dynamic random access memorycells arranged in a matrix of rows and columns. Each semiconductordynamic random access memory cell includes a transistor having a sourceregion, a drain region, a electrically floating body region disposedbetween and adjacent to the source region and the drain region, and agate spaced apart from, and capacitively coupled to, the body region.Each transistor includes a first state representative of a first chargein the body region, and a second data state representative of a secondcharge in the body region. Further, each row of semiconductor dynamicrandom access memory cells includes an associated source line which isconnected to only the semiconductor dynamic random access memory cellsof the associated row.

In one embodiment of this aspect of the present invention, each memorycell of each row of semiconductor dynamic random access memory cellsincludes a separate bit line which is connected to the drain region ofthe associated transistor. In operation, each memory cell of a first rowis programmed to a first data state by applying a control signal, havinga first amplitude, to the gate of the transistor of each memory cell ofthe first row and a control signal, having a second amplitude, to thedrain of each memory cell of the first row. Thereafter, a predeterminedmemory cell of the first row may be programmed to a second data state byapplying a control signal, having a third amplitude, to the gate of thetransistor of the predetermined memory cell, a control signal, having anfourth amplitude, to the drain of predetermined memory cell, and acontrol signal, having a fifth amplitude, to the source of predeterminedmemory cell of the row. Notably, unselected memory cell(s) of the firstrow is/are maintained in the first data state, while the predeterminedmemory cell is programmed to a second data state, by applying a controlsignal, having a third amplitude, to the gate of the transistor of thepredetermined memory cell and a control signal, having an sixthamplitude, to the drain of predetermined memory cell.

The memory cells of the first row may be read by applying a controlsignal, having a seventh amplitude, to the gate of the transistor of thepredetermined memory cell and a control signal, having an eighthamplitude, to the drain of predetermined memory cell. Notably, all ofthe memory cells of a second row (an unselected row) are maintained inan inhibit state while the memory cells of the first row are read. Inone embodiment, the memory cells of the second row are maintained in aninhibit state (while the memory cells of the first row are read) byapplying a control signal having a ninth amplitude to the gate of thetransistors of the memory cells of the second row.

In one embodiment, the each memory cell of a first row of semiconductordynamic random access memory cells shares a drain region with a memorycell in a second row of semiconductor dynamic random access memorycells, wherein the first and second rows of memory cells are adjacentrows. In another embodiment, each gate of each memory cell of a firstrow of semiconductor dynamic random access memory cells is connected toa first gate line. In yet another embodiment, the gate of each memorycell of the first row of semiconductor dynamic random access memorycells is connected to the first gate line.

In another principal aspect, the present invention is a semiconductormemory array comprising a plurality of semiconductor dynamic randomaccess memory cells arranged in a matrix of rows and columns. Again,each semiconductor dynamic random access memory cell includes atransistor having a source region, a drain region, a electricallyfloating body region disposed between and adjacent to the source regionand the drain region, and a gate spaced apart from, and capacitivelycoupled to, the body region. Each transistor includes a first staterepresentative of a first charge in the body region, and a second datastate representative of a second charge in the body region.

In this aspect, the each row of semiconductor dynamic random accessmemory cells includes (1) an associated source line which is connectedto only the semiconductor dynamic random access memory cells in theassociated row and (2) a different gate line for each semiconductordynamic random access memory cells in the associated row.

In one embodiment of this aspect of the present invention, each memorycell of each row of semiconductor dynamic random access memory cellsincludes a separate bit line which is connected to the drain region ofthe associated transistor. In operation, each memory cell of a first rowis programmed to a first data state by applying a control signal, havinga first amplitude, to the gate of the transistor of each memory cell ofthe first row and a control signal, having a second amplitude, to thedrain of each memory cell of the first row. Thereafter, a predeterminedmemory cell of the first row may be programmed to a second data state byapplying a control signal, having a third amplitude, to the gate of thetransistor of the predetermined memory cell, a control signal, having afourth amplitude, to the drain of predetermined memory cell, and acontrol signal, having a fifth amplitude, to the source of predeterminedmemory cell of the row. Notably, unselected memory cell(s) of the firstrow is/are maintained in the first data state, while the predeterminedmemory cell is programmed to a second data state, by applying a controlsignal, having a third amplitude, to the gate of the transistor of thepredetermined memory cell and a control signal, having a sixthamplitude, to the drain of predetermined memory cell.

The memory cells of the first row may be read by applying a controlsignal, having a seventh amplitude, to the gate of the transistor of thepredetermined memory cell and a control signal, having an eighthamplitude, to the drain of predetermined memory cell. Notably, all ofthe memory cells of a second row (an unselected row) are maintained inan inhibit state while the memory cells of the first row are read. Inone embodiment, the memory cells of the second row are maintained in aninhibit state (while the memory cells of the first row are read) byapplying a control signal having a ninth amplitude to the gate of thetransistors of the memory cells of the second row.

In one embodiment, the each memory cell of a first row of semiconductordynamic random access memory cells shares a drain region with a memorycell in a second row of semiconductor dynamic random access memorycells, wherein the first and second rows of memory cells are adjacentrows. In another embodiment, each gate of each memory cell of a firstrow of semiconductor dynamic random access memory cells is connected toa first gate line.

Again, there are many inventions described and illustrated herein. ThisSummary of the Invention is not exhaustive of the scope of the presentinvention. Moreover, this Summary is not intended to be limiting of theinvention and should not be interpreted in that manner. While certainembodiments, features, attributes and advantages of the inventions havebeen described in this Summary, it should be understood that manyothers, as well as different and/or similar embodiments, features,attributes and/or advantages of the present inventions, which areapparent from the description, illustrations and claims, which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of the detailed description to follow, reference will bemade to the attached drawings. These drawings show different aspects ofthe present invention and, where appropriate, reference numeralsillustrating like structures, components, materials and/or elements indifferent figures are labeled similarly. It is understood that variouscombinations of the structures, components, materials and/or elements,other than those specifically shown, are contemplated and are within thescope of the present invention.

FIG. 1A is a schematic representation of a semiconductor DRAM array asillustrated (and described) in the Semiconductor Memory Device PatentApplication;

FIG. 1B illustrates a memory cell according to the Semiconductor MemoryDevice Patent Application;

FIGS. 2A and 2B are exemplary schematic illustrations of the chargerelationship, for a particular memory state, of the floating body,source and drain regions of a memory cell according to the SemiconductorMemory Device Patent Application;

FIGS. 3A–3C are exemplary schematic and general illustrations of thecharge relationship and charge pumping phenomenon caused by pulsingbetween positive and negative gate biases (during read and writeoperations) of the memory cell of FIG. 1B;

FIG. 4 is a tabulation of exemplary voltage pulse levels that may beemployed in a method of a first embodiment of the present invention;

FIG. 5 is a tabulation of exemplary voltage pulse levels that may beemployed in a method of a second embodiment of the present invention;

FIG. 6 is a tabulation of exemplary voltage pulse levels that may beemployed in a method of a third embodiment of the present invention;

FIG. 7 is a tabulation of exemplary voltage pulse levels that may beemployed in a method of an embodiment of the present invention;

FIG. 8 illustrates an exemplary word (gate) line voltage waveform to beused in a method of a fourth embodiment of the present invention;

FIG. 9 illustrates an exemplary word (gate) line voltage waveform to beused in a method of a fifth embodiment of the present invention;

FIG. 10 illustrates a timing relationship between exemplary word (gate)line and the bit line voltage waveforms of the fourth embodiment of thepresent invention;

FIG. 11 is a schematic representation of semiconductor DRAM memorydevice according to an aspect of present invention;

FIG. 12 is a schematic representation of column sense and refreshcircuitry that may be employed in the semiconductor DRAM memory deviceof FIG. 11;

FIGS. 13A, 13B, 14A and 14B illustrate a memory array including aplurality of memory cells having a separate source line array thatdefine a particular row of memory cells, and exemplary writing and/orprogramming techniques (including exemplary programming voltage values),according to another aspect of the present invention;

FIGS. 15A and 15B illustrate read operations, including exemplary readoperation voltage values, according to an embodiment of the presentinvention, for the memory array of FIGS. 13A, 13B, 14A and 14B;

FIG. 16 illustrates an exemplary layout of the memory array of FIGS.13A, 13B, 14A and 14B;

FIGS. 17 and 18 illustrate another memory array architecture including aplurality of memory cells having a common source line array, and writingand/or programming techniques (including exemplary programming voltagevalues), according to another aspect of the present invention;

FIG. 19 illustrates exemplary read operation voltage values, accordingto an embodiment of the present invention, for the memory array of FIGS.17 and 18;

FIG. 20 illustrates an exemplary layout of the memory array of FIGS. 17and 18;

FIG. 21 illustrates a memory array including a plurality of memory cellshaving a separate source line array (that define a particular row ofmemory cells) and gates lines that are parallel to associated bit lines,and exemplary writing and/or programming techniques (including exemplaryprogramming voltage values), according to another aspect of the presentinvention;

FIG. 22 illustrates exemplary read operation voltage values, accordingto an embodiment of the present invention, for the memory array of FIG.21;

FIG. 23 illustrates an exemplary layout of the memory array of FIGS. 21and 22;

FIGS. 24 and 25 illustrate another memory array architecture including aplurality of memory cells having a common source line array, and writingand/or programming techniques (including exemplary programming voltagevalues), according to another aspect of the present invention;

FIG. 26 illustrates exemplary read operation voltage values, accordingto an embodiment of the present invention, for a memory array of FIGS.25 and 26;

FIG. 27 illustrates an exemplary layout of the memory array of FIGS. 24and 25;

FIG. 28 illustrates an exemplary configuration of a dual-port or amulti-port memory cell, according to another aspect of the presentinvention; and

FIG. 29 illustrates an exemplary layout of the dual-port or a multi-portmemory cell of FIG. 28.

DETAILED DESCRIPTION

There are many inventions described and illustrated herein. In a firstaspect, the present invention is directed to a memory device andtechnique of reading data from and writing data into memory cells of thememory device. In this regard, in one embodiment of this aspect of theinvention, the memory device and technique for operating that devicethat minimizes, reduces and/or eliminates the debilitating affects ofthe charge pumping phenomenon. This embodiment of the present inventionemploys control signals that minimize, reduce and/or eliminatetransitions of the amplitudes and/or polarities.

With reference to FIGS. 1 and 4, in one embodiment, transistor 14 (a0.25 micron N-channel MOSFET DRAM cell) may be operated using theexemplary voltage values. In this regard, a write logic low (binary datastate “0”) operation, in one exemplary embodiment, may be written byapplying a word line (i.e., gate bias) voltage of 2.9V, and the bit line(here, a drain bias) voltage of 2.3V. In this operation, the source linevoltage is maintained at 0V. Under these conditions, the junctionbetween body region 18 and source region 20 is forward biased, andexcess holes are removed from body region 18 into source region 20.

To perform a write logic high (binary data state “1”) in transistor 14,a voltage of 0.6V is applied to gate 16 (i.e., the gate bias is held at0.6V) and a voltage of 2.3V is applied to drain 22. In response, anelectric current between source region 20 and drain region 22 providingimpact ionization in body region 18, which in turn generates excessmajority carriers (holes) in body region 18. Note that the gate voltageof unselected cells (holding voltage) is kept at 0V. It is found thatthese exemplary voltages avoid strong accumulation of holes at theinterface of gate oxide 32 and floating body region 18 wherein minoritycarriers 34 have a tendency to be “trapped” by or in defects within thesemiconductor. In this way, disturbance of data caused by charge pumpingis suppressed, reduced, minimized and/or eliminated.

In a second embodiment, with reference to FIGS. 1 and 5, transistor 14(a 0.25 micron N-channel MOSFET DRAM cell) may be operated using theexemplary voltage values indicated. In this regard, to write a logichigh (binary data state “1”), a strong accumulation of majority carriersat the interface of gate oxide 32 and floating body region 18 isrequired. In one exemplary embodiment, a voltage of −1.7V is applied togate 16 and a voltage of 1.7V is applied to drain region 22 to providethe strong accumulation of majority carrier at the interface of gateoxide 32 and floating body region 18. These control signals causedeformation of the valence and conduction bands at the interface betweenbody region 18 and source region 20. As a result, minority carriers(here, electrons) are injected into the conduction band by means of atunnel effect (an effect known as gate induced drain leakage (GIDL)),which in turn causes the generation of majority carriers (here, holes)in body region 18. This operating technique has an advantage in thathole generation occurs in a non-conducting state of transistor 14. Inthis way, majority carrier generation may be achieved at a relativelylower power consumption.

To perform a read data operation, in one embodiment, an inversionchannel is created at the interface of gate oxide 32 and floating bodyregion 18. This may be achieved by applying a voltage of 0V to gate 16and drain region 22 (i.e., a gate bias of 0V) and a voltage of −0.5V tosource region 20.

In a third embodiment, with reference to FIGS. 1 and 6, transistor 14 (a0.13 micron technology DRAM cell) may be programmed and/or operatedusing the exemplary voltages indicated. The voltages set forth in FIG. 6represent “ideal” conditions, in which the application of the voltagepulses does not disturb the data stored within the cell. However, thecells are arranged in matrices in which some cells are accessed whenothers remain un-accessed, and column and row decoding are thereforenecessary to enable the matrices to function. This results in voltagelevels differing from the levels being applied during write, read andhold operations (in practice, all of the cells that share either thesame column or row with the addressed memory cell), as a consequence ofwhich disturbance of the data stored within those cells may occur.

An example of this is shown in FIGS. 1 and 7, in which data state “0” isbeing written to memory cell 12 at the intersection of the selected wordline and bit line. Since all cells in the same column of FIG. 1 sharethe same gate voltage and all cells in the same row as FIG. 7 share thesame drain voltage, voltages different from the “ideal” holding voltagesare applied to those memory cells, as a result of which charge may leakfrom the floating body regions of those cells.

Similar arrangements occur when writing logic high (i.e., data state“1”) or reading the data from memory cells 12. It is found(experimentally) that a worst case is represented by writing logic low(i.e., data state “0”), and memory cells 14 may sustain a few hundredcycles of word line switching, and over 10,000 cycles of bit lineswitching. It can therefore be seen that fluctuations in the gatevoltage may impose limitations on the architecture of the circuit, andin particular, if it is assumed that only 100 cycles of word linepulsing are permissible, this small number of cycles could eithernecessitate partitioning the rows to smaller length (e.g., 64) orrefreshing all cells along the word line as frequently as on a prior artDRAM involving transistors and capacitors.

Both of these arrangements are extremely inefficient since they couldsignificantly increase the number of word line drivers or senseamplifiers required to operate the circuit. Furthermore, because eachdata cell is smaller (4F2) than a conventional DRAM cell (8F2), thecircuit layout may be either impossible or extremely expensive toachieve.

With reference to FIGS. 8, 11 and 12, in one embodiment, the number ofword line drivers and/or sense amplifiers are reduced and/or minimized.In this regard, a column decoder is disposed or arranged between the bitlines and the sense amplifiers to reduce and/or minimize the number ofsense amplifiers and, in conjunction, while only one cell in a block(typically 8 or 16) is read. The memory cell on a column defined by aninternal counter (for example, among 8 or 16) and on a row defined byuser addresses is read and thereafter, refreshed. That cell then isavailable for user access (via read or write operation) at the same rowand column defined by the user addresses.

From a signaling perspective, with reference to FIG. 8, the variationsor swings of the amplitude, as well as the polarity, of the gatevoltages are reduced and/or minimized in number and rising/fallingedges. Notably, a read or write operation of a predetermined memory cellmay occur prior to the refresh operation. (See, for example, FIG. 9).

With reference to FIGS. 11 and 12, the semiconductor DRAM memory deviceof this aspect of the present invention includes a plurality of matrices40 a–n, each including a plurality of memory cells 12 (comprised oftransistors 14). The memory cells 12 are arranged in arrays having rowsand columns, which may be addressed by content address memory (CAM) 42and column refresh counter 44. The column address output from columnrefresh counter 44 is applied to column address multiplexer 46. Thecolumn address multiplexer 46 receives the refresh address and the useraddress and provides one of the addresses to a column multiplexer 48 toselect one of, for example, eight or sixteen bit lines (columns) 28 a.

In order to enable memory cells 12 to be refreshed during, for example,idle periods (i.e., when there is no user access), memory cell 12 at theintersection of a given or selected row and a given or selected columnis addressed by applying a signal on row address bus 50 to all of theinterconnected gates of the row and a signal on column address bus 52 toall of the interconnected drains of the column. The row to be refreshedis identified by row refresh counter 54, which is gated, via row addressmultiplexer 56, with a row address from user address bus 58.

The column refresh counter 44 supplies a column address of a column tobe refreshed. As mentioned above, the column address is gated, viacolumn address multiplexer 46, with a column address from user addressbus 58. As a result, the data state of memory cell 12 at theintersection of the selected row and column is determined and re-writtento memory cell 12. The column refresh counter 44 may then increment inresponse to the same row being chosen, as a result of which the columnsare sequentially addressed for each row, regardless of the order inwhich the rows are addressed. This provides the advantage of minimizingthe risk that a memory cell 12 fails to be refreshed within theappropriate period. Depending on the phase during access, the columnaddresses are received from row refresh counter 44 or from user addressbus 58, and when, for example, the device (or portion thereof) is idle,the row addresses are provided by row refresh counter 54.

Notably, the refresh technique and circuitry of FIG. 11 may be used withseveral arrays in parallel, as a result of which the number of senseamplifier 60 may be reduced and/or minimized (as is the area requiredfor such circuitry on the die).

With reference to FIG. 12, when a column is selected, the signal onWLDPW line 62 provides a power supply voltage to word line drivers 62a–x, according to the phase in the cycle waveform. The columnmultiplexer 48 addresses the column (and therefore the selected memorycell) to be refreshed, and the data in the selected memory cell is readby sense amplifier 60, the result being output (i.e., DATA signal) onsignal line 66.

According to the signal logic levels on line 62 (after conversion byvoltage converter 68) and line 66, the write conditions applied to theword line are as follows: During write “1” condition, if the DATA signalis “1”, XNOR logic gate 68 outputs, on signal line 68, a logic high(i.e., binary “1”) which is amplified by write amplifier 72 and thenapplied to the selected memory cell in order to restore the data statein the selected memory cell. If the DATA signal is “0”, a logic low(i.e., “0”) is applied to the bit line, which represents a holdingcondition. While writing data state “0”, on the other hand, if the DATAsignal is “0”, the XNOR logic gate 68 outputs a logic high (i.e., binary“1”), which is amplified by write amplifier 72 and then applied to thememory cell to restore its data. If the DATA signal is “1”, a “0” isapplied to the bit line, which again represents a holding condition.

In certain embodiments, it may be advantageous to further reduce,minimize and/or eliminate any issues of disturbance (for example, issuesof stored charge loss or gain within memory cells) of the data states ofmemory cells having common gate lines, drain lines and/or source lineswith those memory cells that are being accessed (i.e., being read fromor written to during, for example, a normal or refresh operation). Inone embodiment, a two-step write operation may be employed to programmemory cell 12 with little to no disturbance to adjacent and/orneighboring cells (i.e., cells that share source lines, drain linesand/or gate lines). In this regard, an entire row of memory cells mayfirst be written to the same logic state and thereafter, individual bitsare written to the opposite state in accordance with a desired datastate (i.e., the individual bits are written to another state to reflecta desired data state).

It is intended that such two step write technique may be employed usingmany different memory cells and many different memory arrayarchitectures, whether now known or later developed; and all such memorycells and different memory array architectures fall within the presentinvention. For example, the write technique may be implemented wherememory cells 12 a–d of each row 80 a–f of transistors have a dedicatedsource line to minimize, reduce and/or eliminate disturbance on adjacentrows (for example, row 80 b versus row 80 c).

With reference to FIGS. 13A and 13B, in one embodiment, a given row 80a–f may be written to by applying a clear operation followed by aselective write operation. In this regard, a plurality of memory cells100, having gates that are connected to a common gate line, are arrangedto form row 80 a. Exemplary voltages that implement a clear operationfor row 80 a and maintain the remaining portion of the array (i.e., rows80 b–f) in a fixed state (i.e., unchanged in response to the clearoperation) are indicated in FIGS. 13A and 13B. In response, the samelogic state (for example, logic high or binary “1”) is stored in memorycells 12 a–d of row 80 a. In this way, the state of memory cells 12 a–dare “cleared”.

Thereafter, individual transistors of memory cells 12 a–d of row 80 aare written to a particular, desired and/or predetermined logic state(see, for example, FIGS. 14A and 14B) in order to store the particular,desired and/or predetermined logic state in memory cells 12 a–d. Inparticular, with reference to FIG. 14A, as described above, memory cells12 a–d are set to logic high (binary “1”) by the clear operation, andthen memory cells 12 b and 12 d are written to logic low (binary “0”).Notably, the logic state of memory cells 12 a and 12 c remains logichigh during the write operation (via applying an inhibit voltage to theassociated bit lines 28 a and 28 c (FIG. 14A). With reference to FIG.14B, memory cells 12 a–d are cleared to logic high (binary “1”) and thenmemory cells 12 a and 12 d are written to logic low (binary “0”). Memorycells 12 b and 12 c remain logic high via a write inhibit voltageapplied to associated bit lines 28 b and 28 c.

With reference to FIGS. 15A and 15B, the data may be read from memorycells 12 a–d of row 80 b by applying the exemplary voltages indicated.An exemplary holding voltage for the remaining portion of the array(including the memory cells of row 80 b–f) is also indicated. Theholding voltage/signal maintains the unselected portion of the array ina fixed state (i.e., unchanged in response to the read operation).Notably, the exemplary read and holding voltages of FIGS. 15A and 15Bmay avoid, reduce and/or minimize charge pumping disturb.

Thus, in this embodiment, the first step of the write operation clearsthe memory cells having a common source line and the second step writesor stores new data or the previous data (in the event that the data didnot change). Array architectures employing this write operationtechnique may have an advantage that the unselected memory cells of thearray are not “disturbed” (or experience little and/or negligibledisturbance) because “high” voltages are applied in the row direction(i.e., on source lines 26) but not in the column direction (i.e., on thedrain or bit lines 28). This write technique may be performed as a pagemode write where the page is first “cleared” and then individual bytes(or bits) in a page are written to a new state.

Notably, the memory architecture, write and/or programming techniques,and read techniques of FIGS. 13A, 13B, 14A, 14B, 15A and 15B may beimplemented in conjunction with the embodiments of the device of FIGS.11 and 12. For the sake of brevity, those discussions will not berepeated.

FIGS. 17–20 illustrate another memory array architecture in which aplurality of memory cells “share” a source line and employ the two-stepwrite technique that may eliminate, minimize and/or reduce disturbanceto memory cells when reading from and/or writing to adjacent memorycells. In this regard, with reference to FIGS. 17 and 18, in oneembodiment, a given row may be written to by applying suitable voltagesto implement a clear operation (FIG. 17) followed by a selective writeoperation (FIG. 18). In conjunction with applying suitable voltages toimplement the clear operation, a write inhibit signal is applied to thegates of memory cells that share a source line 26 (for example, a writeinhibit signal may be applied to the gates of the memory cell of row 80b). Notably, any disturbance on unselected, adjacent row 80 b (withrespect to row 80 a), may avoid, reduce and/or minimize by biasing wordline 24 b to an intermediate value that balances write logic low (i.e.,write “0”) and write logic high (i.e., write “1”) operation.

In particular, exemplary voltages that implement a clear operation forrow 80 a and maintain the neighboring memory cells (for example, memorycells of row 80 b) remaining portion of the array in a fixed state(i.e., unchanged in response to the clear operation) are indicated inFIG. 17. The memory cells 12 a–d of row 80 a are written to aparticular, desired and/or predetermined logic state (see, for example,FIG. 18 (write “0”) in memory cell 12 a and memory cell 12 d and (write“1”) in memory cell 12 b and memory cell 12 c) in order to store aparticular, desired and/or predetermined logic state of memory cell 12.

With reference to FIG. 19, the data may be read from memory cells 12 a–dof row 80 a by applying the exemplary voltages indicated. Notably, anexemplary holding voltage for the remaining portion of the array(including the neighboring memory cells of row 80 b as well as thememory cells of rows 80 c–f) is also indicated. The holdingvoltage/signal maintains the unselected portion of the array in a fixedstate (i.e., unchanged in response to the read or write operation).

The memory architecture, write and/or programming techniques, and readtechniques of FIGS. 17–20 may be implemented in conjunction with theembodiments of the device of FIGS. 11 and 12. For the sake of brevity,those discussions will not be repeated.

Another memory array architecture that may employ a one-step writetechnique that eliminates, minimizes and/or reduces disturbance tomemory cells when reading from and/or writing to adjacent memory cellsis illustrated in FIGS. 21–23. In this architecture, source lines 26 areseparated for each row 80 a–e. In addition, word lines 24 a–d arearranged parallel to associated bit lines 28 a–d, respectively.

With reference to FIG. 21, in one embodiment, a given row may be writtento by applying suitable voltages to directly implement a write operation(see, memory cells 12 a–d of row 80 a). In conjunction with applyingsuitable voltages to implement the write operation, a write inhibitsignal is applied to source lines 26 b–e of rows 80 b–e, respectively.Exemplary voltages that implement the write operation (for memory cells12 a–d) and the inhibit state (for the memory cells of rows 80 b–e) areindicated in FIG. 21. The memory cells 12 a and 12 d of row 80 a aremaintained and/or written to a particular, desired and/or predeterminedlogic state (here, write “1”) and memory cells 12 b and 12 c are writtento a different desired and/or predetermined logic state (here, write“0”).

With reference to FIG. 22, the data may be read from memory cell 12 a ofrow 80 a by applying the exemplary voltages indicated. Notably, anexemplary read inhibit voltage for the remaining portion of the array(including the other memory cells of row 80 a and the memory cells ofrows 80 d–e) is also indicated. The read inhibit voltage/signalmaintains the unselected portion of the array in a fixed state (i.e.,unchanged in response to the read operation).

The memory architecture, write and/or programming techniques, and readtechniques of FIGS. 21–23 may be implemented in conjunction with theembodiments of the device of FIGS. 11 and 12. For the sake of brevity,those discussions will not be repeated.

Another memory array architecture that may employ the two-step writetechnique that eliminates, minimizes and/or reduces disturbance tomemory cells when reading from and/or writing to adjacent memory cellsis illustrated in FIGS. 24–27. In this architecture, the source linesare shared but bit lines are separated so each memory cell on eitherside of a source line, for example memory cells 12, has a dedicated bitline. The gates of transistors 12 a and 12 e may be connected togetherat the array boundary.

Notably, memory cells 12 a and 12 e are located on separate rows withthe gates of each transistor 12 a and 12 e connected at, for example,the array boundary. In this embodiment, there is a separate bit line(here, drain lines 28 a and 28 e) for each memory cell 12 a and 12 e sothat each transistor 12 a and 12 e may be read separately.

With reference to FIGS. 24–27, in one embodiment, a given pair of rowsmay be written to by applying suitable voltage to implement a clearoperation (FIG. 24) followed by a selective write operation (FIG. 25).The pair of rows (for example, rows 80 a and 80 b) corresponding tomemory cells 12 a and 12 e, on either side of a common source line, arewritten and read (FIG. 26) simultaneously.

Notably, the memory architecture, write and/or programming techniques,and read techniques of FIGS. 24–27 may be implemented in conjunctionwith the embodiments of the device of FIGS. 11 and 12. For the sake ofbrevity, those discussions will not be repeated.

There are many inventions described and illustrated herein. Whilecertain embodiments, features, materials, configurations, attributes andadvantages of the inventions have been described and illustrated, itshould be understood that many other, as well as different and/orsimilar embodiments, features, materials, configurations, attributes,structures and advantages of the present inventions that are apparentfrom the description, illustration and claims. As such, the embodiments,features, materials, configurations, attributes, structures andadvantages of the inventions described and illustrated herein are notexhaustive and it should be understood that such other, similar, as wellas different, embodiments, features, materials, configurations,attributes, structures and advantages of the present inventions arewithin the scope of the present invention.

For example, as mentioned above, the illustrated voltage levels toimplement the write and read operations are exemplary. The indicatedvoltage levels may be relative or absolute. That is, for example, alogic low may be written into transistor 102 a (see, for example, FIG.13A) using the voltages indicated therein. Alternatively, the voltagesindicated may be relative in that each voltage level, for example, maybe increased or decreased by a given voltage amount (for example, eachvoltage may be increased by 0.25 volts).

Moreover, while a significant portion of this description includesdetails (for example, clear, write, read and inhibit voltages) directedto N-channel transistors, the inventions (and embodiments thereof,described herein are entirely applicable to P-channel transistors. Insuch embodiments, majority carriers 30 in body region 18 are electronsand minority carriers 34 are holes. Indeed, the memory arrays ofmatrices 40 a–n may be comprised of N-channel, P-channel and/or bothtypes of transistors. Moreover, the circuitry that is peripheral to thememory array (for example, row and column address decoders, notillustrated herein, as well as comparators) may include P-channel and/orN-channel type transistors, including transistors like transistor 14.

Notably, where P-channel type transistors are employed as memory cells12 in the memory array(s) of matrices 40 a–n, suitable clear, write,read and inhibit voltages are well known to those skilled in the art inlight of this disclosure. Accordingly, for sake of brevity, thesediscussions will not be repeated.

Further, memory cell(s) 12 (as well as memory array and matrices 40 a–n)may also employ the structure, features, attributes, architectures,configurations, materials, techniques and advantages described andillustrated in non-provisional patent application entitled“Semiconductor Device”, which was filed on Feb. 18, 2004, by Fazan andOkhonin, and assigned Ser. No. 10/487,157 (hereinafter “SemiconductorDevice Patent Application”). The entire contents of the SemiconductorDevice Patent Application, including, for example, the inventions,features, attributes, architectures, configurations, materials,techniques and advantages described and illustrated therein, are herebyincorporated by reference herein.

Furthermore, the memory transistors and/or cells, and method ofoperating such transistors and/or cells, of the present invention may beimplemented in many different configurations. For example, the floatingbody regions of two or more transistors may be shared to realize adual-port or a multi-port memory cell. In this regard, with reference toFIG. 28, a dual port memory cell 12 a may include transistors 14 a and14 b. A dual port memory array may include a plurality of dual portmemory cells 12 arranged, for example, in a matrix of rows and columns.The data state defined by the amount of carriers in the commonelectrically floating body region 18 is common to the two transistors 14a and 14 b.

The read and write access operations may be performed independently fortransistors 14 a or 14 b, using the respective independent word lines24, source line 26 and bit lines 28. In the illustrative example, sourceline 26 is common to the transistors 14 a and 14 b of memory cell 12 a.Notably, the source regions of transistors 14 a and 14 b may beconnected to separate source lines.

With reference to FIG. 29, in an exemplary layout, dual port memory cell12 a includes a P+ floating body node 18 that “connects” a P− floatingbody region under gate 24 m of transistor 14 a with a P− floating bodyregion under gate 24 n of transistor 14 b. The gates 24 m and 24 n areconnected to word lines 24 m and 24 n, respectively. The source regions20 a and 20 b are connected to respective source lines. The drainregions 22 a and 22 b are connected to drain lines. Notably, asmentioned above, although this description includes details directed toN-channel transistors, the inventions (and embodiments hereof areentirely applicable to P-channel transistors. In such embodiments,majority carriers in body region 18 are electrons, and minority carriersare holes.

1. A semiconductor memory array, comprising: a plurality ofsemiconductor dynamic random access memory cells arranged in a matrix ofrows and columns, each semiconductor dynamic random access memory cellincludes at least one transistor having: a source region; a drainregion; a body region disposed between the source region and the drainregion, wherein the body region is electrically floating; and a gatespaced apart from, and capacitively coupled to, the body region; whereineach memory cell includes (1) a first data state which corresponds to afirst charge in the body region of the transistor of the memory cell,and (2) a second data state which corresponds to a second charge in thebody region of the transistor of the memory cell; and wherein the sourceregion of the transistor of each memory cell corresponding to a firstrow of semiconductor dynamic random access memory cells and a second rowof semiconductor dynamic random access memory cells is connected to afirst source line, and wherein the first and second rows of memory cellsare adjacent rows and the gate of the transistor of each memory cellcorresponding to the first row of semiconductor dynamic random accessmemory cells is connected to a first word line and the gate of thetransistor of each memory cell corresponding to the second row ofsemiconductor dynamic random access memory cells is connected to asecond word line; and wherein one or more predetermined memory cells ofthe first row are programmed to the second data state by programmingeach memory cell of the first row to the first data state and thereafterprogramming the one or more predetermined memory cells of the first rowto the second data state.
 2. The semiconductor memory array of claim 1wherein the transistor of each memory cell of the first row ofsemiconductor dynamic random access memory cells shares a source regionwith a transistor of an adjacent memory cell of a second row ofsemiconductor dynamic random access memory cells.
 3. The semiconductormemory array of claim 2 wherein the drain region of the transistor ofeach memory cell of the first row of semiconductor dynamic random accessmemory cells is connected to a bit line that is different from the bitline of the adjacent memory cell of the second row of semiconductordynamic random access memory cells.
 4. The semiconductor memory array ofclaim 2 wherein each memory cell of the first row is programmed to thefirst data state by applying a control signal, having a first amplitude,to the gate of the transistor of each memory cell of the first row, acontrol signal, having a second amplitude, to the drain region of thetransistor of each memory cell of the first row and a control signal,having a third amplitude, to the source region of the transistor of eachmemory cell of the first row.
 5. The semiconductor memory array of claim4 wherein the one or more predetermined memory cells of the first roware programmed to the second data state by applying (1) a controlsignal, having a fourth amplitude, to the gate of the transistor of eachmemory cell of the one or more predetermined memory cells, (2) a controlsignal, having an fifth amplitude, to the drain region of the transistorof each memory cell of the one or more predetermined memory cells, and(3) a control signal, having a sixth amplitude, to the source region ofthe transistor of each memory cell of the one or more predeterminedmemory cells of the first row.
 6. The semiconductor memory array ofclaim 5 wherein an unselected memory cell of the first row is maintainedin the first data state, while the one or more predetermined memorycells are programmed to the second data state.
 7. The semiconductormemory array of claim 1 wherein the first word line and the second wordline are connected.
 8. The semiconductor memory array of claim 1 whereinmemory cells of the first row of semiconductor dynamic random accessmemory cells and the second row of semiconductor dynamic random accessmemory cells are read from or written to simultaneously.
 9. Asemiconductor memory array, comprising: a plurality of semiconductordynamic random access memory cells arranged in a matrix of rows andcolumns, each semiconductor dynamic random access memory cell includesat least one transistor having: a source region; a drain region; a bodyregion disposed between the source region and the drain region, whereinthe body region is electrically floating; and a gate spaced apart from,and capacitively coupled to, the body region; wherein each transistorincludes a first state representative of a first charge in the bodyregion, and a second data state representative of a second charge in thebody region; and wherein: the source region of the transistor of eachmemory cell corresponding to a first row of semiconductor dynamic randomaccess memory cells is connected to a first source line; the gate of thetransistor of each memory cell corresponding to the first row ofsemiconductor dynamic random access memory cells is connected to a firstword line; the drain region of the transistor of each memory cell of thefirst row of semiconductor dynamic random access memory cells isconnected to a different bit line; and the source region of thetransistor of each memory cell corresponding to a second row ofsemiconductor dynamic random access memory cells is connected to thefirst source line; the gate of the transistor of each memory cellcorresponding to the second row of semiconductor dynamic random accessmemory cells is connected to a second word line; the drain region of thetransistor of each memory cell of the second row of semiconductordynamic random access memory cells is connected to a different bit line;and wherein the first and second rows of semiconductor dynamic randomaccess memory cells are adjacent rows; and wherein one or morepredetermined memory cells of the first row are programmed to the seconddata state by programming each memory cell of the first row to the firstdata state and thereafter programming the one or more predeterminedmemory cells of the first row to the second data state.
 10. Thesemiconductor memory array of claim 9 wherein the transistor of eachmemory cell of the first row of semiconductor dynamic random accessmemory cells shares a source region with a transistor of an adjacentmemory cell of a second row of semiconductor dynamic random accessmemory cell.
 11. The semiconductor memory array of claim 10 wherein thedrain region of the transistor of each memory cell of the first row ofsemiconductor dynamic random access memory cells is connected to a bitline that is different from the bit line of the adjacent memory cell ofthe second row of semiconductor dynamic random access memory cells. 12.The semiconductor memory array of claim 11 wherein each memory cell ofthe first row is programmed to a the first data state by applyingcontrol signal, having a first amplitude, to the gate of the transistorof each memory cell of the first row of semiconductor dynamic randomaccess memory cells, a control signal, having a second amplitude, to thedrain region of the transistor of each memory cell of the first row ofsemiconductor dynamic random access memory cells, and a control signalhaving a third amplitude, to the source region of the transistor of eachmemory cell of the first row of semiconductor dynamic random accessmemory cells.
 13. The semiconductor memory array of claim 12 wherein theone or more predetermined memory cells of the first row of semiconductordynamic random access memory cells are programmed to the second datastate by applying a control signal, having the fourth amplitude, to thegate of the transistor of each memory cell of the one or morepredetermined memory cells, a control signal, having a fifth amplitude,to the drain region of the transistor of each memory cell of the one ormore predetermined memory cells, and a control signal, having a sixthamplitude, to the source region of the transistor of each memory cell ofthe one or more predetermined memory cells.
 14. The semiconductor memoryarray of claim 13 wherein an unselected memory cell of the first row ofsemiconductor dynamic random access memory cells is maintained in thefirst data state, while each memory cell of the predetermined memorycells are programmed to the second data state, by applying a controlsignal, having the fourth amplitude, to the gate of the transistor ofthe unselected memory cell and a control signal, having an seventhamplitude, to the drain region of the transistor of the unselectedmemory cell.
 15. The semiconductor memory array of claim 9 wherein allof the memory cells of the second row are maintained in an inhibit statewhile the memory cells of the first row are read.
 16. The semiconductormemory array of claim 9 wherein the transistor of each memory cell ofthe first row of semiconductor dynamic random access memory cells sharesa drain region with the transistor of an adjacent memory cell of thesecond row of semiconductor dynamic random access memory cells.
 17. Thesemiconductor memory array of claim 9 wherein the first word line andthe second word line are connected.
 18. The semiconductor memory arrayof claim 9 wherein memory cells of the first row of semiconductordynamic random access memory cells and the second row of semiconductordynamic random access memory cells are read from or written tosimultaneously.
 19. A semiconductor memory array, disposed in or on asemiconductor region or layer which resides on or above an insulatingregion or layer of a substrate, the semiconductor memory array,comprising: a plurality of semiconductor dynamic random access memorycells disposed in or on the semiconductor region or layer and arrangedin a matrix of rows and columns, each semiconductor dynamic randomaccess memory cell includes at least one transistor having: a sourceregion; a drain region; a body region disposed between the sourceregion, the drain region and the insulating region or layer of thesubstrate, wherein the body region is electrically floating; and a gatespaced apart from, and capacitively coupled to, the body region; whereineach memory cell includes (1) a first data state which corresponds to afirst charge in the body region of the transistor of the memory cell,and (2) a second data state which corresponds to a second charge in thebody region of the transistor of the memory cell; and wherein the sourceregion of the transistor of each memory cell corresponding to a firstrow of semiconductor dynamic random access memory cells and a second rowof semiconductor dynamic random access memory cells is connected to afirst source line, and wherein the first and second rows of memory cellsare adjacent rows and the gate of the transistor of each memory cellcorresponding to the first row of semiconductor dynamic random accessmemory cells is connected to a first word line and the gate of thetransistor of each memory cell corresponding to the second row ofsemiconductor dynamic random access memory cells is connected to asecond word line; and wherein one or more predetermined memory cells ofthe first row are programmed to the second data state by programmingeach memory cell of the first row to the first data state and thereafterprogramming the one or more predetermined memory cells of the first rowto the second data state.
 20. The semiconductor memory array of claim 19wherein the transistor of each memory cell of the first row ofsemiconductor dynamic random access memory cells shares a source regionwith a transistor of an adjacent memory cell of a second row ofsemiconductor dynamic random access memory cells, wherein the first andsecond rows of memory cells are adjacent rows.
 21. The semiconductormemory array of claim 20 wherein the drain region of the transistor ofeach memory cell of the first row of semiconductor dynamic random accessmemory cells is connected to a bit line that is different from the bitline of the adjacent memory cell of the second row of semiconductordynamic random access memory cells.
 22. The semiconductor memory arrayof claim 19 wherein the transistor of each memory cell of the first rowof semiconductor dynamic random access memory cells shares a drainregion with the transistor of an adjacent memory cell of the second rowof semiconductor dynamic random access memory cells.
 23. Thesemiconductor memory array of claim 19 wherein the first word line andthe second word line are connected.